Transient hepatic attenuation difference (THAD), in MRI sometimes called transient hepatic intensity differences (THID), is presented in this case in a segmental shape secondary to portal vein thrombosis and thus secondary to portal hypoperfusion. It shows the most signal and density difference to the rest of the liver in the arterial perfusion phase due to hepatic arterial compensatory flow. 

Differential diagnoses should include:

• focal hypervascular lesions, such as hepatocellular carcinoma
• inflammatory lesions
• liver trauma
• arterioportal shunt